hot shots. Jeans are a special type of what are called tool kit jeans, and these toolkit jeans are small subset of genes that control and organisms development, a k a. The genes we've been talking about this whole time right those genes important to development, so we often are to get a little more specific. A subset of tool kit genes are these home idiotic genes, which are genes that control the development of specific anatomical structures, and Hawks jeans, which hawks that actually comes from home. Idiotic box. So hawks for short hocks jeans are a type of homoerotic gene homoerotic jeans, and they're highly conserved genes, meaning that they've been around for a really long time through the course of evolution. And they help control development along that anterior to post cheerier access. They're activated after segments form. So might remember there those segment genes that we just mentioned on the previous page. So after all that they come towards the end of development and they help determine the specific structures that will form in a segment. So here we have a nice example. You can see this fruit fly very common model organism to use in biology, and you can see how the fruit fly has been divided into different segments represented by different colors here. And you can see that each segment is associate ID with a particular jean these air all hawks jeans, and they're going to lead to the development of the specific anatomical structures you see present at those segments. So initially, like you saw in the previous page, this embryo just kind of looks like a segmented blob. But through the activation of these hawks genes, specific animal anatomical structures will develop now. Development in general is a highly conserved process, and it's directly linked toe evolution. Which is why, when you look at the embryo formation of different animals, for example, we tend to all look the same in the beginning and then slowly branch out and become different. It's because the developmental process has been passed along through evolution. So even though, for example, fish are not a whole lot like us during development, we actually have gills. Yes, you and I had gills at one point in our life when we were a fetus, we develop gills and then we lost them, and that is because development is so heavily are so highly conserved and is directly links toe evolution. And guess what? There were fish before there were people. So we kind of, you know, carry on some of those traits to this day. But they Onley are present during our development. Now another, uh, another facet of this conservation of the developmental process is the fact that many animals use the same genes and chemical signals to govern body plan development, sea hawks, jeans, very important, highly conserved jeans there. And one last interesting thing to note about development is that many of the same chemical signals are used repeatedly during the course of development. But depending on when and how they're used, they actually will elicit different effects. And this again is just another case in point of how conserved everything is in biology. Biology is not wasteful. Rather, it takes things that already has and repurpose is them to its new needs. So development, highly highly conserved process with a direct link to evolution. And you can see here in this image how these developing embryos all look very similar. Um and this is another reason we use or we or we can use organisms like chickens or sea urchins. For example, toe learn Maura about our own human development because there's so many links. There's so much crossover between the development of a chick or even a sea urchin, believe it or not, and a person. All right, that's all I have for this video. I'll see you guys next time.